Bio110 Final Review
Bio110 Final Review Bio110
University of Louisiana at Lafayette
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Chapter 2 Orbitals- the region of space surrounding nucleus where there is a high probability of finding that electron. Can only carry two electrons per orbital. Orbitals occupy electron shells (energy levels) Atomic number = protons. Protons = electrons in an atom. Row and period tell number of electron shells white columns and groups tell the number of valence electrons. Atomic mass are averages of different isotopes of an element. Measured in daltons. Protons + neutrons A mole of any substance contains the same number of particles as there are atoms in 2g of carbon. 12gC = 1 mol C, 1gH = 1 mol H. One mole of any element contains 6.02x10^23 atoms. Isotopes have different neutrons. Rutherford found that the nucleus has the mass of an atom. Hydrogen, oxygen, carbon, and nitrogen make up 95% of organisms Molecular formula O2, chemical symbol and subscript. Structural formula: H-F, H-O-H Bonds- bonds involve electrons exchanged directly between two atoms while interaction molecules will act a certain way Covalent- often the strongest type of bond o polar- unequal sharing of electrons. Water o nonpolar- equal sharing of electrons Ionic- gained or lost electrons. Cations have a net positive charge while anions are negative. Salt Hydrogen bonds- must be polar hydrogen atom pairing Van Deer Wals forces- weakest type of interaction Hydrophobic- water-fearing. Nonpolar Hydrophilic- water loving. Polar Amphipathic molecule have polar or ionized regions at one site or more and nonpolar regions at others. Micelles- polar at surface/outer with nonpolar region in the center Water less dense as a solid, high specific heat/heat of vaporization, has cohesion on high surface tension. (Adhesive- sticks to each other, cohesion- sticks to something else) Solution has a solvent (liquid) and solute (substance being dissolved in solvent) Acids are ph 6 or below, bases/ alkaline solutions are ph 8 or above. Molecular mass = sum of all atomic masses in a molecule Molarity= # of moles of solute per 1 liter heat of vaporization= heat to vaporize 1 mole @ boiling point heat of fusion= amount of energy withdrawn to change liquid -> solid specific heat= amount of energy needed to raise temperature by 1 degree Celsius colligative properties= depend on # of dissolved solutes. Addition of solutes to water lowers its freezing point and raises its boiling point. Chapter 3 Wohler proved vitalism to be incorrect. Organic molecules can be made without a vital life force Amino NH2 amino acids (proteins) polar Carboxyl –COOH amino acids, fatty acids, acidic Phosphate –PO4 nucleic acids, ATP, phospholipids. polar, weakly acidic Sulfate –SO4 carbohydrates, proteins, lipids. polar, negative Isomers- same chemical formula, different structures Structural isomers- same atoms in different bonding relationships Stereoisomers- identical bonding relationships, but the spatial positioning differs o geometric- positioning around double bond. have different chemical properties cis-trans: bonding on same side is cis, bonding on opposite sides are trans. o enantiomers- mirror image of another molecule. same chemical properties, different ways of noncovalently bonding to other molecules I. Carbohydrates- carbon/hydrogren/oxygen. C atoms are linked to H atom and hydroxyl group monomers- monosaccharides. disaccharides are two monosaccharides like sucrose (fructose + glucose) glycosidic bond- bond between two sugar molc by dehydration reactions polysaccharides: starch- not branched. plants/energy glycogen- branched. animal/energy cellulose- coiled. plants/cell wall structure chitin- structural. insects. contains nitrogen glycosaminoglycan- structural. animals (cartilage) II. Lipids- hydrophobic. hydrogen/carbon/ some oxygen. Nonpolar, insoluble in water. fats/phospholipids/steroids triglycerides- glycerol bonded with fatty acid chain of C, H, carboxyl. ester bond links glycerol with fatty acid chain through dehydration reactions. store energy saturated: single covalent bond. solid. unsaturated: kinks. liquid. exist in cis form. artificial trans are bad! one kink= monounsaturated two more more kinks= polyunsaturated phospholipids- 3 hydroxyl group of glycerol is linked to phosphate group instead of a fatty acid. the phosphate group is the polar hydrophilic region and the fatty acid chain is nonpolar/hydrophobic. (amphipathic) steroids- four fused rings of carbon atoms. have 1+ polar hydroxyl groups but are not water soluble III. Proteins- C/H/O/N/S. monomers – amino acid (carbon + amino group + carboxyl group) peptide bond- covalent between carboxyl and amino group. polypeptides are many AA’s joined by a peptide bond. N terminus- free amino group, C terminus- free carboxyl group protein is one ore more polypeptides into 3D with a particular function primary: AA sequenece determined by genes nucleic acids- phosphodiester secondary: helix & pleated sheet hydrogen bonds bonds tertiary: 3D and interactions with AA side chains. disulfidlipids- ester bonds quaternary: multiple tertiarys together. IV. Nucleic Acids storage/expression/transmission of genetic information. monomers – nucleotide 2 classes: DNA & RNA. Nucleotide is phosphate group w/ pentose sugar and a single/double ring Chapter 4 Cell theory by Shleiden, Shwann & Virchow 1. all living things are composed of one or more cells 2. cells are smallest unit of living organisms 3. new cells come only from pre-existing cells Hooke coined the word “cell” Light microscope- uses light .2microm Electron microscope-uses an election bream. Resolution 2 nm Transmission electron (TEM) thin slices Scanning (SEM) 3D image Prokaryotic cell: lack membrane enclosed nucleus. categories: bacteria and archaea (found in extreme environments). Lack endomembrane. Bacteria: plasma membrane, cytoplasm, nucleoid, ribosomes (protein synthesis), cell wall, glyocalyx (traps water/ protection), appendages such as pili (attachment) and flagella (locomotion) Eukaryotic cell: have nucleus, compartmentalization, and organelles. Plants have a central vacuole, cell wall, and chloroplast. Molecular Machines- object that has moving parts and does use work. Spontaneously ATP synthase, ribosome site of translation, proteasome (protein degradation), cytoskeleton Cytoskeleton- cell organization and structure o microtubules: longest. made from tubulin. o intermediate filaments: flexible and stable. made from many different proteins o actin filaments: also known as microfilaments. made from actin. smallest o motor proteins: use ATP to promote movement. o flagella: 9+2. 9 sets of 2 microtubules Sheetz and Spudich confirmed that myosin is a motor protein that uses ATP to walk on actin filaments Organelles- catabolism is breakdown of a molecule into smaller components while anabolism is the synthesis of cellular molecules and macromolecules Endomembrane system- network of membranes enclosing nucleus, ER, GA, lysosomes & vacuoles ER- o rER- protein synthesis, sorting and modification o sER- detox, lipids GA- stores and organizes. Secretion, processing, and protein sorting. Cis takes things from the ER Lysosomes- recycles cells Vacuoles- storage semiautonomous organelles: mitochondria, chloroplast, peroxisome Glycosylation- attachment of a carb to a protein (glycoprotein) Chapter 5 Phospholipid bilayer- hydrophobic tail faces in, hydrophilic heads face out Fluid mosaic model- lipids and proteins can move relative to each other. integral membrane proteins (all the way across) trans membrane proteins- one or more regions that are physically embedded in the hydrophobic region Lipid anchors- covalent attachment to lipid to amino acid in protein Peripheral membrane system noncovalently bound to regions of integral membrane proteins that project out from the membrane, or they are bound to the polar head groups of phospholipids Fluidity- molecules remain in close association yet have the ability to move within the membrane Semifluid- most lipids can rotate freely and move laterally Flipflop can occur with ATP and an enzyme Factors affecting fluidity: length of fatty acid tail (short react less, making membrane more fluid) double bonds ( kinks= more fluid) cholesterol (keeps the membrane from becoming too solid in cold and keeps it from becoming too fluid in high temps.) Glycosylation can serve as recognition signals and cell surface recognition/ cell coat protective effects Hypertonic solution- solute concentration is higher on one side of the membrane Transport of ions, atoms, and molecules across cell does not require energy Passive transport- does not require energy passive diffusion- diffusion of solute through membrane without tansport protein facilitated diffusion- solute through membrane with aid of a transport protein Osmosis- diffusion of water Plasmolysis- plants wilt because water leaves plant cells Crenation- shrinking in hypertonic solution Turgor pressure- plasma membrane against cell wall maintains shape Transport proteins channels- often passive; aquaporins o ligand: chemically gated o intracellular regulatory proteins, phosphorylation, voltage-gated, mechanosensitive transporters- do not use energy but change conformation; slower than channels o uniporter- single o symporter/contransporter- 2 molc in same direction o antipoter- 2 molc different directions o pumps: transporters that use energy ATP driven pumps Active transport- movement of solute against ts gradient from a region of low to high concentration primary- directly uses energy secondary- uses preexisting gradient Chapter 6/7 Anabolic- linking together, producing stored energy, endogonic Catabolic-breaking molecules apart, releasing energy, exergonic thermodynamics- first law: energy cannot be created/destroyed, second: entropy H (enthalpy/total energy) = G (work) + TS (heat) spontaneous reactions occur without input. free energy charge. △G is negative exergonic- G < 0, negative endergonic- G > 0, positive catalysts lower activation energy cofactor- inorganic coenzyme- organic. leaves unchanged in reaction phosphorylation- phosphate group is added to something. you get energy Metabolic Pathways gene regulation: turn on/off genes cellular: cell signaling pathways (channels) biochemical regulation: o competitive inhibitors (active site), o noncompetitive (bind outside), allosteric- causes conformational change in enzyme active site inhibiting enzyme function, feedback- product of pathways inhibits early steps to prevent overaccumalation of product Redox- oxidation (loses e), reduction (gains e) 2 ways to make ATP: substrate level phosphorylation **oxygen not needed** chemiosmosis (oxidative phosphorylation) makes ATP from ATP+P Anaerobic metabolism- uses different electron acceptor and carries out glycolysis only. primary metabolism- essential for cell structure and function secondary- synthesis of secondary metabolites that are not necessary for cell structure and growth. roles in defense, attraction, protection, competition. alkaloids- bitter tasting molecules for defense polyketides- chemical weapons phenolics- antioxidants with intense flavors and smells terpenoids- intense smell and colors Cellular Respiration Chapter 8 CO2 + H20 + light energy -> C6H12O6 + O2 + H20 photosynthesis 2 Stages of photosynthesis: light reactions (thylakoid membrane, produces ATP/NADPH/O2) Calvin Cycle (stroma, uses ATP & NADPH to put CO2 in organic molecules) Light Photosystem II: absorbs photons, removes electron from H20 P680 Photosystem I: makes NADPH. Gets electron from plastocyanin P700 noncyclic: PSII -> NADPH. produces ATP & NAPH equally cyclic: electron cycles, releases energy to transport H and only makes ATP Dark Calvin Cycle- ATP & NADPH is used to make carbohydrates. Uses more ATP than NADPH for every 6CO2, 18ATP and 12 NADPH is used 3 phases: o 1) carbon fixation: CO2 in RuBP using rubisco 6C -> 2 3PG o 2) reduction: ATP is used to convert 3PG into 1,3 biphosphateglycerate. NADP electrons reduce it to G3P. 6CO2 -> 12 G3P o 3) regeneration: 6 ATP is used to make 10 G3P -> 6 RuBP light intensity/ temperature / water affects the Calvin Cycle Photorespiration RuBP + CO2 -> 2 3PG using o2 and liberating CO2 is wasteful. Occurs when CO2 is low on hot/dry day RuBP + O2 -> 3PG + phosphoglycolate (toxic) C4 plants separate rubisco from o2 spacially in a bundle sheath cell. Has advantage in warm, dry climates CAM separates rubisco from o2 temporally (time) Fermentation- NAD is limiting molecule. pyruvate is reduced (no O2) glycolysis occurs (anaerobic) and uses pyruvate Chapter 11 Genetic material must contain the info necessary to construct an organism, pass from parent to offspring, and cell to cell during cell division, be accurately copied, and account for the known variation within/between species chromosomes carry proteins and nucleic acids Griffith: transformation. Formation of capsule is governed my genetic material. Evidence that molecules carry genetic inf Avery, Macleod, McCarty used purification methods to reveal that DNA is the genetic material Hershey & Chase determined that DNA is the genetic material of T2 bacteriophage Levels of DNA structure: nucleotide, DNA, double helix, proteins to form chromosomes, genome Linkage in DNA/RNA is phosphodiester (phosphate sugar backbone) Waston & Crick proposed the double helix DNA structure Franklin did x rays to suggest helical structure Chargoff’s rule: A=T/U, G=C DNA has ten base pairs per turn. Major groove is where proteins bind. Semiconservative: one parent one daughter Conservative: parent strands stay together Dispersive: each strand has segments of daughter and parent Meselson and Stahl found semiconservative to be correct DNA helicase travels 5’-3’ DNA topoisomerase relieves coiling ahead of helicase Single-strand binding protein keeps template open DNA polymerase- covalently links nucletoides unable to begin synthesis without short RNA primer made by DNA primase can only read 5’-3’ Deoxynucleoside triphosphates- free nucleotide with three phosphate groups that break covalent bonds to release pyrophosphate and provides energy to connect adjacent nucleotides Leading Strand DNA primase makes RNA primer DNA polymerase attaches nucleotides in 5’-3’ as it slides forward Lagging DNA is synthesized 5’-3’ away from fork direction primase makes short RNA primers called Okazaki fragments DNA polymerase replaces RNA with Dna DNA ligase joins the DNA fragments Telomeres are a series of repeat sequences in DNA and special proteins that do not have a complementary strand. 3’ overhang cannot be copied by polymerase. Telomerase prevents chromosome shortening. Attaches repeated DNA sequences to telomeres. Provides site for RNA primer. Loses function with age Chapter 12 Beadle & Tatum one gene one enzyme hypothesis. (more accurate is the one gene- one polypeptide) Genes control the protein and the protein codes for everything else gene- group of nucleotides on a specific chromosome that calls for a protein. Organized unit of DNA that is transcribed into RNA. 90% of genes are structural (mRNA) Transcription (DNA -> mRNA) 1) Initiation- recognition step. In bacteria, sigma factors recognizes promoter region 2) Elongation- RNA polymerase synthesizes RNA after release of sigma factor. open complex 10/15 base pairs long. template/coding strand if DNA is used for RNA synthesis. “sense” strand. 5’-3’. U=T. DNA rewinds after RNA polymerase 3) Termination- RNA polymerase reaches termination sequence. RNA is always 5-3’ and DNA is always 3’-5’ a. RNA polyermase II transcribes mRNA while I & III transcribe nonstructural genes for rRNA/tRNA i. RNA polymerase II requires 5 transcription factors to begin transcription RNA processing Does not occur in prokaryotic cells. Introns are cut out and exons are kept for translation into mRNA. Introns are removed by splycosome composed of snRNPs (nuclear RNA & proteins). Introns in rrna and trna are self splicing. 5’ cap has meth and is needed for proper exit of nucleus. 3’ Tail has 100-200 adenine nucleotides that increases stability and lifespan in the cytosol. Translation (RNA -> polypeptide) genetic code- sequence of bases in mRNA. start codon: AUG. stop codon: UAA/UAG/UGA tRNA anticodon binds to codon aminoacyl-tRNA synthetase attaches amino acid to tRNA (20 different types). The second genetic code- aminoatrnas recognizing appropriate tRNA ribosomes prokaryotics have one kind of ribosome 1) Incitation – mRNA, first tRNA, and ribosomal subunits assemble. Requires help from ribosome incitation factors and GTP. In bacteria, mRNA binds to ribosome by a ribosomal- binding sequence. Eukaryotic mRNA have 7-met cap and 5’ end recognized by cap proteins 2) Elongation- aminiacyl-tRNA brings amino acid to A site of ribosome. Peptide tRNA is in the P site. Peptide bonds form between amino acids. Peptidyl transfer reaction- polypeptide from tRNA in P site goes to A site 3) Termination at stop codon is recognized by release factors Chapter 15 Chromosomes contain the genetic material. Genes are in chromosomes. Chromosome are made of DNA and proteins. Before the cell can divide, DNA is folded into chromosomes. Chromatin is a DNA-protein complex unfolded. DNA wraps itself around histone proteins- nucleosomes are DNA wrapped around 8 of these histone proteins. Transcription cannot happen in this form. Histones have amino terminal tails. Nucleosomes are 30nm in diameter. Heterochromatin- highly compact and transcriptionally inactive Euchromatin- capable of gene transcription. Preperation for cell division: replicated DNA, sister chromatids, and centromere Cell Cycle: G1, S, G2 (interphase), PMAT (m phase) ends with cytokinesis (division of cell cytoplasm) G1- time varies by organism S- DNA replication G2- set time. proteins Mitosis: asexual division of chromosomes. can cause cancer Prophase- mitotic spindle is complete and centrosomes move apart Metaphase- sister chromatids are aligned halfway to poles in a single row Anaphase- connection between the sister chromatids are broken and each chromatid is linked to a pole and pulled away Telophase- nuclear membrane reforms and produce 2 nuclei Cytokinesis- in animals, the membrane pinches. in plant cells, it builds a new cell wall Meiosis: sexual reproduction. haploids are produced from diploids. Happens after Mitosis and another round of G1, S, and G2. Prophase I- replicated chromosomes condense and bivalents form. crossing over occurs Metaphase I- bivalents (homologous sister chromatids lying side by side, aka synapsis) form double row in the center Anaphase I- chromatid pairs move to one pole Telophase I- nuclear membrane forms Cytokenisis- produces haploids but do not have a homologous chromosome pair Meiosis II: occurs directly after Meiosis I, G1, and G2 phase. No s phase here. PMAT is the same as mitosis Mitosis produced 2 diploid daughters wile meiosis produces four haploid cells Mitosis/Meiosis II looks like: Meiosis I: Chapter 16 Mendel’s Law of Segregation: 2 copies of gene segregate from each other during the transmission from parent to offspring Law of independent assortment- alleles of different genes assort independently of each other during gamete formation Chromosome theory of inheritance- chromosomes contain the genetic material, chromosomes are replicated and passed from parent to offspring, the nucleus of a diploid cell contains two sets of chromosomes, at meiosis, one member of each chromosome pair segregates, gametes are haploid cells that combine to form a diploid cell during fertilization Locus- physical location of a gene on a chromosome Incomplete dominance- one allele for a specific trait is not completely dominant over another allele. Neither allele is dominant. PKU Codominance- single individual expresses two alleles. Blood type. Sex linked- baldness, color blindness, hemophilia Chapter 51 Types of asexual reproduction: budding, regeneration, parthenogenesis (development of unfertilized eggs) Gametogenesis- production of egg and sperm in humans Spermatogenesis- primary spermatocytes undergo meisos I to produce 2 haploid secondary spermatocytes, then undergo meiosis II to produce 4 haploid spermatids and eventually become sperm. Testosterone Gonadotropin-releasing hormone made by the hypothalamus stimulates anterior pituitary to release lutenizing hormone and follicle-stimulating horome LH stimulates Leydig cells to produce testosterone FSH stimulates sertoili cells and spermatogenesis Oogenesis- females will only form 1 gamete from each primary oocyte Ovarian cycle- if there is no pregnancy, corpus luteum degenerates and a new set of follicles begin developing Follicular phase- first half when growth and differentiation follicle occurs of the ovarian cycle Luteal phase- when the corpus luteum develops and secrets progesterone Uterine (menstrual) cycle- 2 phases: proliferative phase (endometrium becomes thicker) and secretory phase (secretes nutritive substances for embryo) Male Epididymis- storage and maturation of sperm Prostate gland- stores and secretes a fluid 1/3 of semen Scrotum- keeps temperature warm Seminal vesicles- contains enzymes and nutrients Seminiferous tubes- creation of sperm Sertoili cells- nurtures and develop sperm Testes- produce male sex hormone Urethra- urine Female Cervix- childbirth Fallopian tubes- egg transportation site Ovaries- maturation of oocyte, synthesizes hormones Uterus- houses developing human Endometrium- contains glands that secrete fluids Chapter 41 Central nervous system- brain and spinal cord Peripheral nervous system- all neurons and projections of their plasma membranes Nervous system Central peripheral Brain, higher thought/ spinal cord autonomic somatic Learning behavior/instinct reflexes (involuntary) (voluntary) sympathetic parasympathetic (fight & flight) (rest & digest) Neurons- cells in nervous system that send and receive chemical signals. All animals but sponges have neurons Cell body / sogma: contains nucleus and organelles Dendrites: extensions of plasma membranes. Incoming singals Axons: extensions of plasma membranes. Sends signals Axon hilloc- near cell body Terminal branches – nerve end Glial cells: supports functions. Most plentiful in nervous system (10 – 10,000 glial cells) -Oligodendrocytes and Shwann cells make myelin sheath -Astrocytes: metabolic support Stem -Microglia: removes cellular debris cells -Radial glial: forms tracks for neuronal migration in embryos Neurons Sensory- detect info Motor- sends signals away from efferent neurons (CNS) Interneurons- form complex connections between neurons Membrane potential Inside the membrane in negative, outside is positive Different in charge between inside and outside. Plasma membrane is selectively permeable to cations and anions. Membrane is polarized. Resting membrane potential- neurons are not sending singals (-70mv) 1. 3 Na+ out of cell exchanges with the 2 K+ inside the cell 2. Membrane is more permeable to the K+ 3. Negative particles are inside the cell # of molc Outside Inside cell cell Na+ more less K+ less more Cl- more less Changes in membrane potential are changes in the degree of polarization -Depolarization: cell membrane is less polarized. Gated channels open, allowing Na+ to flow into the cell and membrane potential becomes more positive -Hyperpolarization: cell membrane becomes more polarized (negative). K+ leaces cell, Cl- enters. Only neurons and muscle cells have the capacity to generate electrical signals. 2 types of changes: Graded potential: any depolarization or hyperpolarization that varies depending on the size of the stimulus. Ex: a resting period would be equilibrium/ homeostasis Action potential: electrical events that carry a signal along an axon. Always a large depolarization. o Begins when graded potential depolorizes to threshold o Na+ channels open at -50mv o Na+ diffuses into cell, causing a spike o Refractory period: Na+ is shut. This is responsible for the axon hillock -> terminal o K+ opens and leaves the cell, making the inside of the cell negative o Too many K+ and the cell hyperpolarizes. Channels close and rest is restored Action potentials are conducted down the axon with great speed; it cannot move backwards. Speed is based off of the axon diameter (faster = bigger) Myellnation (sheath) Node of ranvier gaps o Salatory conduction = action potentials, jumping from node to node ~~At the axon terminal~~ Synapses: junction where the nerve terminal meets a neuron, muscle, and gland cell 1) Presynaptic cell sends signal 2) Synaptic cleft- space betweens neurons 3) Postsynaptic 2 types of synapses: 1) Electrical- flow through junction from cell to cell 2) Chemical- neurotransmitter acts as signal from presynaptic to postsynaptic Excitatory- depolarizes Inhibitory- hyperpolarizes Neurotransmitters: Acetylcholine- one of the most widespread, released at junctions, excitatory in brain/skeletal muscle but inhibitory in cardiac muscles Biogenic amines/ amino acids/ neuropeptides/ gaseous Muscle: group of cells bound together. One unit of myofibrils = sarcomere Thick filaments = myosin thin = actin/troponin/tropomyosin Sliding filament theory: each tropo/tropomyosin chain has an actin site which contains a binding site for myosin Calcium reacts with troponin and make tropomyosin slide off the active site Cross bridge cycle: events between when crossbridge binds to thin filament and repeats 1) Binds to actin 2) Filaments slide past eachother 3) ATP binds to myosin, crossbridge detatches 4) Hydrolysis of ATP reenergizes the cross bridge Tropomyosin: molecule with 2 proteins along the actin Troponin: smaller protein bound to 2 proteins and an actin. Binds Ca+ and drags the tropomyosin off Chapter 42 3 divisions of vertebrate brain -Hindbrain: metencephalon – pons, cerebellum myelencephalon - medulla oblongata -Midbrain: mesencephalon – midbrain - Forebrain: telencephalon – cerebrum Diencephalon – thalamus, hypothalamus, epithalamus Hindbrain Medulla oblongata: basic reflexes, homeostasis, heart rate, breathing, ect Cerebellum + pons: conductor of body movement (graceful). Pon is relay. Maintains balance and hand-eye coordination Pons + midbrain = brain stem. Contains nuclei that connects to other brain parts Midbrain Forms part of a reticular foration that keeps on alert or conscious Processes sensory inputs like vision/smelling/hearing Forebrain Diencephalon Thalamus: sensory information, receives sensory input from all sensory systems Hypothalamus: hormone production, pituitary gland regulation Telencephalon Basal nuclei: planning and learning movements, initiating/inhibiting movements Limbic system: formation/expression of emotions o Amygdala – understanding and remembering emotional situations. Recognizes emotions in others o Hippocampus- establish memories for spatial locations/facts/moves short term memory into long term memory Cerebral cortex: gray matter on cerebrum. Voluntary acts/speech/learning/memory o Frontal- conscious thought and social awareness o Parietal- attention and associating events with incoming information o Occipital- vision o Temporal- language, learning, and some memory Left hemisphere of the brain understands language and producing speech Right hemisphere controls nonverbal memories, recognizes faces, and interprets emotions Human nervous system Cranial nerves are connected directly to the brain Spinal nerves are connections between PNS & spinal cord White matter- myelinated axons grouped together Gray matter- neuronal cell bodies, dendrites, and some unmyelinated axons o Spinal cord is gray matter Dorsal horns- incoming sensory information Ventral horns- outgoing sensory information CNS is encased in bone and 3 layers of meninges Dura matter- outer thich layer Arachnoid- connections to inner pia mater (inner thin membrane) Cerebrospinal fluid circulates between arachnoid and pia mater to absorb physical shocks, trasnports ventricles, and central canal PNS division Somatic nervous system o Sensory neurons receive heat, vision, smell, taste, hearing, touch and transmit it to CNS. Motor neurons control skeletal muscles (voluntary) Autonomic nervous system o Composed of motor neurons that control smooth muscle, cardiac muscle, glands (involuntary). Sensory neurons detect internal body conditions Sympathetic division – flight/fight, heart rate increases Parasympathetic division- rest/digest, heart rate decreases Chapter 43 Sensory transduction: incoming stimuli is converted into neural signals or action potentials Perception: awareness of sensations Sensory receptor: recognizes stimulus and initiates signal transduction by creating graded potentials in the same or adjacent cells. Found in neurons and epithelial cells Intensity: amount of depolarization is directly related to intensity of stimulus. More light/chemical/pressure creates more of a signal. When a stimulus is strong enough, it will depolarize the membrane to threshold. Strength/type of stimulus is indicated by frequency of action potentials generated. Higher frequency = more intense Mechanoreceptors: transduce mechanical energy Thermoreceptors: respond to cold and heat Nociceptors (pain) respond to extreme heat/cold/pressure and acids Electromagnetic receptors: detect radiation within spectrum Photoreceptors: visible light energy Chemoreceptors: respond to specific chemicals Mechanoreceptors Touching/deforming opens to ion channels Skin receptors: o Meissner’s corpuscles: sense touch and light pressure beneath the skin surface o Pacinian corpuscles: deep pressure/vibration. Pancreas. Deeper skin surface Stretch receptors: deforms. Causes depolarization Hair cells: ion channels open/close when cilia bends o Cilia of hair cells protrude into the capula in lateral line system (capula moves -> hair bends -> neurotransmitter released) Equilibrium/proprioception: ability to sense position/orientation/movement of body. Invertebrates have statocysts (crawfish ball) Vestibular systems in vertebrates is located in the inner ear next to the cochlea. Utricle and saccule detect linear movements of the head o When the head moves, inertia causes calcium carbonate otoliths to lag behind and bend cilia, changing the membrane potential Semicircular canals detect 3D. hair cells are embedded in gelatinous capula. When the head moves, fluid in the canal shifts in the opposite direction, pushing on capula and behind hair. Audition (ability to detect sound waves) Sound waves are horizontal. Wavelengths: peak of wave to the next peak Frequency: number of complete wavelengths in a second Mammalian Ear 1. Outer ear: pinna and auditory canal a. Separated by ear drum (tympanic membrane) 2. Middle ear: ossicles (hammer/anvil/stirrup) connects ear drum to oval window a. The cochlea and vestibular systems are separated by the oval window 3. Inner ear: cochlea and vestibular system a. Eustachian tube: equalizes pressure between middle ear and atmospheric pressure Sound waves enter the outer ear -> tympanic membrane vibrates back and forth -> ossicles transfer vibration from tympanic membrane to oval window -> sound waves change mechanical pressure as ear drums moves -> the movement sends pressure waves through cochlea -> waves travel from vestibular canal to tympanic canal and dissipate against round window -> higher frequency sounds we hear pass though basilar membrane, making it vibrate Mechanical forces transduced into electrical signals by organ of corti. Hairs bending in one direction sends action potential. Hairs bending in other direction shut off the neurotransmitter release. When the cilia move, ion channels that are mechanoreceptors are opened. This allows depolarization of the hair cell membrane. This is a graded potential that will cause neurotransmitters to be released causing an action potentioal in the auditory nerve. Basilar membrane is lined with protein fibers Thermoreceptors Respond to either hot or cold temperatures by activating and inhibiting enzymes within the plasma membrane, altering membrane channels. Cold receptor endings are closer to the skin. Can detect core body temperature. Nocireceptors Nerve endings in the skin and internal organs. Respond to tissue damage or stimuli about to cause tissue damage. Thermoreceptors and Nocireceptors are chemoreceptors. Molecules act on the receptors causing a graded potential to occur and action potential to follow. Electromagentic sensing: detects radiation in spectrum including visible/ultraviolet/infrared Photoreception Detects photons of light arriving from sun Planaria (worm) eyecup contains photoreceptor endings that detect presence/absent of light. No visual images. Compound eyes (arthropods) o Many light detectors (ommoatidia) o Lens and crystalline cone focus light onto rhabdon Single-lens eye (verterbrates) o Light is transmitted through pupil to retina. Photoreceptors trigger electrical charges Sclera: strong outer white sheath Cornea: continuous with sclera, but thin and clear 2 cavities: anterior holds aqueous humor, posterior holds thick vitreous humor that maintains eye shape Iris: pigmented smooth muscle controlling size of pupil. Autonomic nervous system Cornea and lens bend incoming light. Lens is adjusted by ciliary muscle Blindspot: in the retina, no optic nerves Fovea: small area of retina behind lens with photoreceptors for color. Responsible for sharpness of daylight vision Rods: black and white, used at night. Contains rhodopsin. Cones: color. o There are more rods than cones in the human eye Photoreceptors have slightly depolarized plasma membrane. The cell hyperpolarizes in response to light stimulus. Depolarizes after continuously releases glutamate. When exposed to light, retinal dissociates from opsin. Opsin changes shape and membrane becomes less positive. Intensity of light = hyperpolarization Retina shape- 3 layers 1. Rods/cones- deepest against sclera 2. Bipolar cells- synapses with ganglion cells 3. Ganglion cells- sends axon from eye to optic nerve Horizontal cells- modify electric signals and define image boundary Amacrine cells- light adaptation and movement sensitivity Photon sight Photons pass through cornea and hits lens -> rods/cones -> rhodopsin absorbs energy -> cis changes to trans retinal and dissociates from opsin -> results in blaching, which causes activation of transducing -> activates enzyme phosphodiesterase -> reduces cGMP -> closes Na channels -> hyperpolarization decreases the neurotransmitter glutamate -> bipolar and ganglion cells fire action potentials -> optic nerves -> brain Adaptions Light intensity: pupil diameter/retinal conformations Eye placement: binocular (forward eyes) monocular (wider range) Tapedum lucidum: enhances light in the dark (cat) Chemoreception Olfaction- smell Gustation- taste Olfactory sensitivity on mammals depends on density of receptor cells Basal cells differentiate into new olfactory receptor cells Olfactory receptor cells have long cilia with receptor to bind odor molecules. Taste buds Chemosensory cells- papillae collect food molecule and direct to sensory receptors in taste buds Visual disorders Glaucoma: aqueous humor cannot drain. High pressure. Damages retinal cells Macular degeneration: photoreceptor cells around fovea is lost Cataracts: protein clouds in lens Deafness Damage to cells in the cochlea/ nerve or brain problems
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